1. Field of the Invention
This invention pertains to improvements in methods and apparatus for the production of filled, edible products, particularly, but not limited to, irregularly shaped products and to the products so formed.
2. Description of the Prior Art
Various types of techniques have been used for injecting into edible products, such as doughnuts or other confection products, a filling material, such as cream or jelly. These devices primarily use some form of extrusion technique for forming the product, then either extrude or inject the filling material into the product while in a yet unformed state, and then finally form the product around the filling material. These various techniques have generally involved very elaborate mechanical mechanisms to control and guide the flow of both the filling material and the product material, and thus have been expensive to manufacture and difficult to maintain.
One problem in injecting the filling material into edible products that are later cooked, as in a fryer, is that the filling material, during the injecting process, is not adequately sealed from the outside surface of the product, preventing the formation of a good bond between the product material at the surface of the product and impairing the quality and appearance of the final product.
Various of the most pertinent techniques known to Applicants for filling doughnut-like products are described in the following U.S. Pat. Nos. 3,452,687; 3,362,355; 3,653,336; 3,196,810; 2,982,231; 1,933,557; 516,648 and 3,807,919.
Our earlier application, Ser. No. 463,155, discloses and claims interalia the concept of controlling the injection of filling material into the product material by applying positive pressure on the filling material to discharge it and applying negative pressure on the filling material to withdraw a portion of it for stopping the discharge. This broad concept was described as being suitable for products of any shape and any type of filling material. This application is an improvement on such earlier application in that it discloses and claims specific products and specific methods and apparatus for making products of various shapes, primarily each with discrete spots of filling material within.
Heretofore, filled edible products were limited in shape and size due to the necessity of injecting the filling material into the product in a manner such that it would not leak out or cause failure of the structure of the product. One attempt at solving this problem for a specific toroidal or doughnut-shaped product is described in U.S. Pat. No. 3,807,919. This patent discloses a filling material injecting nozzle which has a mechanical valve that opens and closes to control the discharge of filling material into the product. Such a mechanical valve frequently leaves a dribble of filling material still flowing when the edible product material is injected around. This dribble creates defects in the product, such as a weak plane in a toroidal shape, because the dribble prevents an adequate bond of the product material around the filling material. Furthermore, the mechanical valving mechanism of U.S. Pat. No. 3,807,919 limits the types, shapes and sizes of products that can be made.